Broadcasts picked up from Guitar Amp

[Abstract Dissonance]

I was playing my guitar amp(digital) today and noticed after turning my
guitars volumn down all the way that I heard some type of voice in the
noise(sorta like those that think they recorded some ghosts talking.)

The first think I captured is something about god or eygpt or something.
The wierd thing is that it fades in and out of clarity and strenght.

Heres a clip of one part. I did some noise reduction to try and make it a
little more clear.

http://www.geocities.com/abstract_dissonance/God.mp3


In the whole thing there sounds like some russian speak and some music. I
played around with the tone and drive controls on my amp to try and see if I
could "tune" it but I don't think I had any luck. That clip has the most
audible sound. Everything else is much harder to hear.

I'm curious as to where this possibily comes from. Is it radio stations or
TV or maybe Ham?

Also, would the problem possibily be from the design of the amp being bad or
is this just noise that happens to be picked up by all equipment? (its not
audiable with normal use of the amp).

One more thing: Why does the sound seem to fade in and out? It seems to do
this in a consistent basis as if there is a low frequency envelope modifying
the stength of the signal.

Thanks,
Jon

P.S. I'm wondering if this is where people that claim to hear god,ghosts,
etc.. get the signals from. At first, when I heard it I wasn't sure what it
was but after some time I heard some voices and it sounded like I was
picking up a phone conversation(like sometimes the wireless phones do).

It made me think of that show about ghosts were they would try and be
scientific and they would record some spot and then claim that they captured
some ghost like voice saying someones name. Most likely they are just
hearing things but then I thought maybe that the internal circuitry might be
picking up signals from something and that might explain it.

 

[phaeton]

I was playing my guitar amp(digital) today and noticed after turning my
guitars volumn down all the way that I heard some type of voice in the
noise(sorta like those that think they recorded some ghosts talking.)

Dewd! Play Stairway!! You're being channeled by Bonham!!


No seriousry. High resistance and high impedance inputs seem to allow
radio waves to be picked up. Those two things are built into your
amplifier, and there is little you can do about it.

Are you using shielded cables? I have a 1.5 foot unsheilded cable that
cna pick up a Mexican mariachi station no matter where I am.

If you unplug the guitar, do the voices go away?

Are you using any effects when you hear the radio signals?

You might be able to shield the guitar (try borrowing a different guitar
and see what you get), or it just may be the amp.


What kind of guitar and amp are these, btw?

-phaeton

 

[Michael Black]

I was playing my guitar amp(digital) today and noticed after turning my
guitars volumn down all the way that I heard some type of voice in the
noise(sorta like those that think they recorded some ghosts talking.)

The first stage of the amplifier is acting like a rectifier, ie a
crystal radio, and converting radio waves into audio that the rest
of the amplifier is amplifying. The cable from the guitar acts
as an antenna. Of course, this works because there is a strong signal
nearby, strong enough to overload that first stage.

It is a common thing, and is a side effect of the active devices. Happens
with both tube and solid state devices. The only variable is whether or not
there is a local signal strong enough to do the overloading.

It is not the fault of the transmitter in this case.

The solution is to keep the radio signals out of that first stage.
The traditional method is a small value capacitor from the base (if
it's a bipolar transistor) or grid (if it's a tube) of the first
active device in the amplifier to ground, using as short leads
as possible. This bypasses the incoming radio signal to ground,
so the first stage can't be affected by it. The trick is to
use a value of capacitor large enough to "short out" the radio
signal, but not so large that it affects the audio response of
the stage.

Note that some equipment will have such capacitors in place, because
they know it can happen.

If you live in a really strong RF field, you may need to get more
complicated, maybe putting an RF choke in series with that element
of the first stage of the amplifier. The stronger the radio signal,
the harder it will be to keep it out.

Michael

 

[Abstract Dissonance]

Dewd! Play Stairway!! You're being channeled by Bonham!!


No seriousry. High resistance and high impedance inputs seem to allow
radio waves to be picked up. Those two things are built into your
amplifier, and there is little you can do about it.

yeah, but radio waves? These are not audible?

Are you using shielded cables? I have a 1.5 foot unsheilded cable that
cna pick up a Mexican mariachi station no matter where I am.

If you unplug the guitar, do the voices go away?

I didn't try.

Are you using any effects when you hear the radio signals?

I'm using a overdrive pedal.

You might be able to shield the guitar (try borrowing a different guitar
and see what you get), or it just may be the amp.


What kind of guitar and amp are these, btw?

Its a Line6 H147.

I'm not worried about the stuff because it doesn't interfere with the guitar
sound as its much much much softer. I was just curious as to where the
sounds were coming from and maybe how they were being picked up.

 

[Abstract Dissonance]

The first stage of the amplifier is acting like a rectifier, ie a
crystal radio, and converting radio waves into audio that the rest
of the amplifier is amplifying. The cable from the guitar acts
as an antenna. Of course, this works because there is a strong signal
nearby, strong enough to overload that first stage.

How does that work? Do you mean there is an sorta of AM demodulation
equivilent circuit in the amp?

It is a common thing, and is a side effect of the active devices. Happens
with both tube and solid state devices. The only variable is whether or
not
there is a local signal strong enough to do the overloading.

It is not the fault of the transmitter in this case.

The solution is to keep the radio signals out of that first stage.
The traditional method is a small value capacitor from the base (if
it's a bipolar transistor) or grid (if it's a tube) of the first
active device in the amplifier to ground, using as short leads
as possible. This bypasses the incoming radio signal to ground,
so the first stage can't be affected by it. The trick is to
use a value of capacitor large enough to "short out" the radio
signal, but not so large that it affects the audio response of
the stage.

Yeah, maybe this happens but since I'm amplifying so much that I can still
get them. like I said, they are barely audible and don't effect normal
playing.

Note that some equipment will have such capacitors in place, because
they know it can happen.

If you live in a really strong RF field, you may need to get more
complicated, maybe putting an RF choke in series with that element
of the first stage of the amplifier. The stronger the radio signal,
the harder it will be to keep it out.

Its not a big deal. Its not loud enough to cause any problems. (Atleast I
think. Maybe it could be the reason why my guitar sound sucks

I was just curious as to where the sounds were comming from and how they
were being picked up.

I was thinking that they could be from AM radio(kinda sounds like an AM
radio) but I don't understand how one could demodulate the signal with
digital equipment(I assume that the amp's first stage is an ADC).

Maybe the signal is being picked up and demodulated in the overdrive pedal I
have... it should be the only analog thing circuitry in the chain.

I didn't try to take it out and see if it made a difference I but next time
when I feel like messing with it I will.

Thanks,
Jon

 

[[email protected]]

I was playing my guitar amp(digital) today and noticed after turning my
guitars volumn down all the way that I heard some type of voice in the
noise(sorta like those that think they recorded some ghosts talking.)

The first think I captured is something about god or eygpt or something.
The wierd thing is that it fades in and out of clarity and strenght.

Heres a clip of one part. I did some noise reduction to try and make it a
little more clear.

http://www.geocities.com/abstract_dissonance/God.mp3


In the whole thing there sounds like some russian speak and some music. I
played around with the tone and drive controls on my amp to try and see if I
could "tune" it but I don't think I had any luck. That clip has the most
audible sound. Everything else is much harder to hear.

I'm curious as to where this possibily comes from. Is it radio stations or
TV or maybe Ham?

Also, would the problem possibily be from the design of the amp being bad or
is this just noise that happens to be picked up by all equipment? (its not
audiable with normal use of the amp).

One more thing: Why does the sound seem to fade in and out? It seems to do
this in a consistent basis as if there is a low frequency envelope modifying
the stength of the signal.

Thanks,
Jon

P.S. I'm wondering if this is where people that claim to hear god,ghosts,
etc.. get the signals from. At first, when I heard it I wasn't sure what it
was but after some time I heard some voices and it sounded like I was
picking up a phone conversation(like sometimes the wireless phones do).

It made me think of that show about ghosts were they would try and be
scientific and they would record some spot and then claim that they captured
some ghost like voice saying someones name. Most likely they are just
hearing things but then I thought maybe that the internal circuitry might be
picking up signals from something and that might explain it.

Try this trick. Put a 1K resistor in series with the signal lead
directly at the input jack and put a ferrite bead on one or both ends
of the resistor lead. My choice woud be on the lead NOT connected to
the jack. That lowpass network will have nearly no effect on the audio
but kill the RF. I've done this on hi end audio receivers, mixing
boards and guitar amps with good results.

GG

 

[jasen]

I was playing my guitar amp(digital) today and noticed after turning my
guitars volumn down all the way that I heard some type of voice in the
noise(sorta like those that think they recorded some ghosts talking.)

The first think I captured is something about god or eygpt or something.
The wierd thing is that it fades in and out of clarity and strenght.

most likely you're picking up CB radio (or some other AM broadcast)
possibly a christian AM radio station.

I'm curious as to where this possibily comes from. Is it radio stations or
TV or maybe Ham?

Probably AM radio and/or CB.

Also, would the problem possibily be from the design of the amp being bad or
is this just noise that happens to be picked up by all equipment? (its not
audiable with normal use of the amp).

Guitar amplifiers are notorious for picking up radio transmissions.

One more thing: Why does the sound seem to fade in and out? It seems to do
this in a consistent basis as if there is a low frequency envelope modifying
the stength of the signal.

are you using a properly designed receiver?

Bye.
Jasen

 

[Michael A. Terrell]

are you using a properly designed receiver?

No, it is a guitar amplifier. Didn't you read what you replied to?


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Michael A. Terrell]

How does that work? Do you mean there is an sorta of AM demodulation
equivilent circuit in the amp?

The input stage is overloaded and forced into a non-linear mode which
will then detect the modulation. The fading is caused by changes in the
RF signal strength being fed to the input, just like any other RF
detector.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Rich Grise]

P.S. I'm wondering if this is where people that claim to hear
god,ghosts, etc.. get the signals from. At first, when I heard it I
wasn't sure what it was but after some time I heard some voices and it
sounded like I was picking up a phone conversation(like sometimes the
wireless phones do).

It made me think of that show about ghosts were they would try and be
scientific and they would record some spot and then claim that they
captured some ghost like voice saying someones name. Most likely they
are just hearing things but then I thought maybe that the internal
circuitry might be picking up signals from something and that might
explain it.

When you're listening to variable noise, you can hear pretty much anything
you want to. My office door opens into a machine shop, and lots of times
when they're turning a large part, the sound of the cutter sounds like
it's saying stuff. Usually something like "Gotcha,gotcha,gotcha,..." ;-)

Or, yes, it could be radio, TV, cell phones, hams, taxicabs, police, fire,
ambulance, aircraft, etc, etc, etc...

Good Luck!
Rich

 

[Bob Eld]

I was playing my guitar amp(digital) today and noticed after turning my
guitars volumn down all the way that I heard some type of voice in the
noise(sorta like those that think they recorded some ghosts talking.)

The first think I captured is something about god or eygpt or something.
The wierd thing is that it fades in and out of clarity and strenght.

Heres a clip of one part. I did some noise reduction to try and make it a
little more clear.

http://www.geocities.com/abstract_dissonance/God.mp3


In the whole thing there sounds like some russian speak and some music. I
played around with the tone and drive controls on my amp to try and see if I
could "tune" it but I don't think I had any luck. That clip has the most
audible sound. Everything else is much harder to hear.

I'm curious as to where this possibily comes from. Is it radio stations or
TV or maybe Ham?

Also, would the problem possibily be from the design of the amp being bad or
is this just noise that happens to be picked up by all equipment? (its not
audiable with normal use of the amp).

One more thing: Why does the sound seem to fade in and out? It seems to do
this in a consistent basis as if there is a low frequency envelope modifying
the stength of the signal.

Thanks,
Jon

P.S. I'm wondering if this is where people that claim to hear god,ghosts,
etc.. get the signals from. At first, when I heard it I wasn't sure what it
was but after some time I heard some voices and it sounded like I was
picking up a phone conversation(like sometimes the wireless phones do).

It made me think of that show about ghosts were they would try and be
scientific and they would record some spot and then claim that they captured
some ghost like voice saying someones name. Most likely they are just
hearing things but then I thought maybe that the internal circuitry might be
picking up signals from something and that might explain it.

It's caused by the detection of some sort of radio signal, most likely a
local, close by AM station. It could be the Ham down the street as well.
The obvious fixes are well shielded, pick-ups, inputs and cables as has been
mentioned .Also, adding small bypass caps, ferrite beads or even series
resistors or inductors may help as well. However, the biggest culprit is not
a lousy front end stage but is rectifying junctions caused by lousy
connectors, jacks, plugs and screw connections. Slight corrosion or oxide on
connections can cause enough non-linearity to detect strong radio signals in
sensitve high gain circuits. The solution: Change out all phone jacks, plugs
and connectors in the low level signal path with GOLD plated ones. That's
why gold is used for high quality contacts. It does not oxidize and will not
cause a rectifying junction. Bad solder joints can do the same thing so
check those as well.
Bob

 

[Bob Myers]

yeah, but radio waves? These are not audible?

They're not audible, but they (especially basic AM radio) aren't
all that difficult to detect (demodulate), either. Remember, this
is something that can be done by a hunk of galena crystal and
a pair of cheap headphones.

Bob M.

 

[JeffM]

The first stage of the amplifier is acting like a rectifier,

ie a crystal radio, and converting radio waves into audio
that the rest of the amplifier is amplifying.
Michael Black

How does that work? Do you mean
there is [a] sorta[...]AM demodulation equivilent circuit in the amp?
Jon (Abstract Dissonance)

Yup. It's called a semiconductor junction (followed by some
capacitance).
http://66.102.9.104/images?q=crystal-set+demodulator
http://hyperphysics.phy-astr.gsu.edu/HBASE/electronic/amfmdet.html
..
..

The solution is to keep the radio signals out of that first stage.
The traditional method is a small value capacitor from the base
[...]or grid[...]to ground

Bob Eld talks about series inductance (a ferrite) as well.
Trap out the unwanted band before it gets demodulated.
..
..

Note that some equipment will have such capacitors in place,
because they know it can happen.

Yup. It's pathetic that the guy who designed the gear
wasn't aware of this phenomenon
and didn't include an appropriate trap.

 

[Abstract Dissonance]

When you're listening to variable noise, you can hear pretty much anything
you want to. My office door opens into a machine shop, and lots of times
when they're turning a large part, the sound of the cutter sounds like
it's saying stuff. Usually something like "Gotcha,gotcha,gotcha,..." ;-)

Or, yes, it could be radio, TV, cell phones, hams, taxicabs, police, fire,
ambulance, aircraft, etc, etc, etc...

yeah

But sometimes it might exactly be saying something

 

[Abstract Dissonance]

The first stage of the amplifier is acting like a rectifier,
ie a crystal radio, and converting radio waves into audio
that the rest of the amplifier is amplifying.
Michael Black

How does that work? Do you mean
there is [a] sorta[...]AM demodulation equivilent circuit in the amp?
Jon (Abstract Dissonance)

Yup. It's called a semiconductor junction (followed by some
capacitance).
http://66.102.9.104/images?q=crystal-set+demodulator
http://hyperphysics.phy-astr.gsu.edu/HBASE/electronic/amfmdet.html
.

cool. I didn't know it was that simple to do AM and FM.

.

The solution is to keep the radio signals out of that first stage.
The traditional method is a small value capacitor from the base
[...]or grid[...]to ground

Bob Eld talks about series inductance (a ferrite) as well.
Trap out the unwanted band before it gets demodulated.
.
.

Note that some equipment will have such capacitors in place,
because they know it can happen.

Yup. It's pathetic that the guy who designed the gear
wasn't aware of this phenomenon
and didn't include an appropriate trap.

 

[Abstract Dissonance]

It's caused by the detection of some sort of radio signal, most likely a
local, close by AM station. It could be the Ham down the street as well.
The obvious fixes are well shielded, pick-ups, inputs and cables as has
been
mentioned .Also, adding small bypass caps, ferrite beads or even series
resistors or inductors may help as well. However, the biggest culprit is
not
a lousy front end stage but is rectifying junctions caused by lousy
connectors, jacks, plugs and screw connections. Slight corrosion or oxide
on
connections can cause enough non-linearity to detect strong radio signals
in
sensitve high gain circuits. The solution: Change out all phone jacks,
plugs
and connectors in the low level signal path with GOLD plated ones. That's
why gold is used for high quality contacts. It does not oxidize and will
not
cause a rectifying junction. Bad solder joints can do the same thing so
check those as well.
Bob

Cool. Thanks for explaining a lot of the issues. I had ideas that it could
possibily be from many of the things you mentioned but wasn't sure if I was
just making stuff up.

Right now its not an issue since it does not effect the overall sound AFAIK.
But atleast if I ever get into the situation where it does then I know whats
going on.

thanks agian,
Jon

 

[Abstract Dissonance]

Try this trick. Put a 1K resistor in series with the signal lead
directly at the input jack and put a ferrite bead on one or both ends
of the resistor lead. My choice woud be on the lead NOT connected to
the jack. That lowpass network will have nearly no effect on the audio
but kill the RF. I've done this on hi end audio receivers, mixing
boards and guitar amps with good results.

I might end up playing around with it later. Right not its not an issue
though. I might just try some of these ideas to see how well they work and
try also to isolate the where the problem is comming from.

Thanks,
Jon

 

[jasen]

jasen wrote:

No, it is a guitar amplifier. Didn't you read what you replied to?

I knew that, I was reminding him. He asked why it faded in and out...

Bye.
Jasen

 

[Michael A. Terrell]

I knew that, I was reminding him. He asked why it faded in and out...

Bye.
Jasen

Which you didn't explain to him.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Rich Grise, Plainclothes Hippie]

Which you didn't explain to him.

That's because nobody really knows. It could be anything from reflections
from traffic, or varying atmospheric conditions, or something in his setup
that's picking up a couple of freq's that are beating with each other, or
it could be the spooks fading in and out, to give their arcane messages.
They can't do it Full-Time, because "God" is watching them, and
disapproves of anything that's not within established "scientific" dogma.

:->

Good Luck!
Rich